Graph Schema Reference

A complete specification of the Aevum Encyclopedia knowledge graph. Defines node labels, relationship types, property constraints, and query patterns for building accurate, traversable knowledge structures.

Note: This schema is backward-compatible. New relationship types and properties are additive. Breaking changes are documented in the versioning section and always preceded by a deprecation notice.

Node Types

The knowledge graph is composed of 8 primary node types. Each node represents a distinct semantic entity within the encyclopedia ecosystem.

Label	Description	Key Properties	Cardinality
Concept	Core topics, ideas, theories, or phenomena	`title`, `description`, `domain`	N
Entity	Physical objects, places, organizations, people	`name`, `type`, `geo_coordinates`	N
Source	Primary references, publications, datasets	`doi`, `publisher`, `year`	N
Contributor	Authors, editors, domain experts	`orcid`, `affiliation`, `role`	N
Category	Taxonomic grouping nodes	`path`, `parent_id`	N
Event	Historical or temporal occurrences	`start_date`, `end_date`, `location_id`	N
Verification	Fact-checking and confidence metadata	`score`, `reviewer_id`, `status`	1..1
Translation	Multilingual variants of concepts	`lang_code`, `localized_title`	1..N

Relationship Types

Relationships define semantic connections between nodes. All edges are directed and may carry typed properties.

Type	Source → Target	Description	Properties
REFERENCES	Concept → Source	Cites or derives from a primary source	`citation_format`, `relevance`
PART_OF	Concept → Category	Taxonomic classification	`confidence`, `reviewed_by`
DEFINED_BY	Concept → Concept	Forms a definitional or logical dependency	`relation_type`
AUTHORED_BY	Source → Contributor	Authorship or editorial contribution	`role`, `order`
OCCURRED_AT	Event → Entity	Spatial-temporal grounding	`geo_hash`, `temporal_range`
RELATED_TO	Concept ↔ Concept	Semantic association or cross-reference	`weight`, `context`
VERIFIED_BY	Concept → Verification	Quality assurance linkage	`method`, `timestamp`

Property Dictionary

Common properties across node types follow strict typing and validation rules. Optional fields are marked with ?.

Validation: All datetime fields must conform to ISO 8601. Numeric confidence scores are floats in [0.0, 1.0]. Text fields are UTF-8 encoded with a 256KB soft limit.

Aevum uses a Cypher-compatible query language with extensions for semantic scoring and temporal filtering. Queries are executed via the `/v2/graph/query` endpoint.

GRAPHQL / CYPHER HYBRID

/* Retrieve high-confidence concepts linked to quantum mechanics */
MATCH (c:Concept {title: "Quantum Mechanics"})
  -[:RELATED_TO*1..2]-> (neighbor:Concept)
WHERE neighbor.confidence_score > 0.85
  AND neighbor.status = "PUBLISHED"
RETURN neighbor.title, neighbor.domain, neighbor.confidence_score
ORDER BY neighbor.confidence_score DESC
LIMIT 25

Pattern Examples

1. Taxonomic Hierarchy Traversal

TAXONOMY TRAVERSAL

MATCH (root:Category {path: "/Science/Physics"})
  WITH root
  MATCH (root)<-[:PART_OF]- (child:Concept)
WHERE child.lang = "en"
RETURN child.title AS topic, 
       count(child) AS article_count
ORDER BY article_count DESC

2. Source Citation Network

CITATION NETWORK

MATCH (paper:Source {year: 2024})
  -[:REFERENCES]-> (ref:Source)
WHERE ref.publisher CONTAINS "Nature"
RETURN paper.doi, 
       collect(ref.title) AS nature_citations,
       size(ref) AS citation_depth

Constraints & Indexes

The schema enforces data integrity through built-in constraints. Indexes are automatically maintained for high-cardinality lookup properties.

UNIQUE(Concept.id) — Primary identifier
UNIQUE(Source.doi) — Digital Object Identifier
UNIQUE(Contributor.orcid) — Researcher identifier
INDEX(Concept.title) FULLTEXT — Semantic search index
INDEX(Concept.domain) — Taxonomic filtering
INDEX(Verification.timestamp) — Audit trail optimization

Schema Versioning

Schema changes follow semantic versioning. Major releases introduce breaking changes; minor releases are additive; patch releases fix validation bugs.

Version	Date	Changes
v2.4.1	2025-06-10	Fixed temporal range validation for `Event` nodes
v2.4.0	2025-05-22	Added `Translation` node type & multilingual indexing
v2.3.0	2025-04-15	Introduced `Verification` graph & confidence scoring
v2.0.0	2024-11-01	Major rewrite: Cypher-compatible engine, normalized properties

Migration Path: Legacy v1.x graphs can be upgraded using the @aevum/migrator CLI tool. Run npx @aevum/migrator schema --target v2.4.1 to auto-convert nodes and relationships.